Answer:The Wright brothers invented and flew the first airplane in 1903, recognized as "the first sustained and controlled heavier-than-air powered flight". ... Airplanes had a presence in all the major battles of World War II. The first jet aircraft was the German Heinkel He 178 in 1939.
Explanation:
Answer:
All of them cause friction
Explanation:
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Answer:
N_A=1.5*10^-8 kmol/s.m^2
Explanation:
<u>KNOWN: </u>
Molar concentration of helium at the inner and outer surfaces of a plastic membrane. Diffusion coefficient and membrane thickness.
<u>FIND:</u>
Molar diffusion flux.
<u>ASSUMPTIONS:</u>
(1) Steady-state conditions, (2) One-dimensional diffusion in a plane wall, (3) Stationary medium, (4) Uniform C = C_A + C_B.
<u>ANALYSIS:</u> The molar flux may be obtained from
N_A=D_AB/L(C_A,1-C_A,2)
=10^-9 m^2/s/0.001 m(0.02-0.005)kmol/m^3
N_A=1.5*10^-8 kmol/s.m^2
<u>COMMENTS:</u> The mass flux is:
n_A,x=M_a*N_A,x
n_A,x=6*10^-8 kg/s m^2
